PPC: [turbofan] Better and more sane support for tail calls

src/compiler/ppc/code-generator-ppc.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/osr.h"
@@ skipping 587 matching lines @@
     if (mode == kMode_MRI) {                                  \
       __ asm_instr(value, operand);                           \
     } else {                                                  \
       __ asm_instrx(value, operand);                          \
     }                                                         \
     __ bind(&done);                                           \
     DCHECK_EQ(LeaveRC, i.OutputRCBit());                      \
   } while (0)
 
 
-void CodeGenerator::AssembleDeconstructActivationRecord() {
+void CodeGenerator::AssembleDeconstructActivationRecord(int stack_param_delta) {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
   int stack_slots = frame()->GetSpillSlotCount();
+  int sp_delta =
+      (stack_param_delta < 0) ? -stack_param_delta * kPointerSize : 0;
   if (descriptor->IsJSFunctionCall() || stack_slots > 0) {
-    __ LeaveFrame(StackFrame::MANUAL);
+    __ LeaveFrame(StackFrame::MANUAL, sp_delta);
+  } else if (sp_delta) {
+    __ Add(sp, sp, sp_delta, r0);
   }
 }
 
 
 // Assembles an instruction after register allocation, producing machine code.
 void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
   PPCOperandConverter i(this, instr);
   ArchOpcode opcode = ArchOpcodeField::decode(instr->opcode());
 
   switch (opcode) {
     case kArchCallCodeObject: {
       v8::internal::Assembler::BlockTrampolinePoolScope block_trampoline_pool(
           masm());
       EnsureSpaceForLazyDeopt();
       if (HasRegisterInput(instr, 0)) {
         __ addi(ip, i.InputRegister(0),
                 Operand(Code::kHeaderSize - kHeapObjectTag));
         __ Call(ip);
       } else {
         __ Call(Handle<Code>::cast(i.InputHeapObject(0)),
                 RelocInfo::CODE_TARGET);
       }
       RecordCallPosition(instr);
       DCHECK_EQ(LeaveRC, i.OutputRCBit());
       break;
     }
     case kArchTailCallCodeObject: {
-      AssembleDeconstructActivationRecord();
+      int stack_param_delta = i.InputInt32(instr->InputCount() - 1);
+      AssembleDeconstructActivationRecord(stack_param_delta);
       if (HasRegisterInput(instr, 0)) {
         __ addi(ip, i.InputRegister(0),
                 Operand(Code::kHeaderSize - kHeapObjectTag));
         __ Jump(ip);
       } else {
         // We cannot use the constant pool to load the target since
         // we've already restored the caller's frame.
         ConstantPoolUnavailableScope constant_pool_unavailable(masm());
         __ Jump(Handle<Code>::cast(i.InputHeapObject(0)),
                 RelocInfo::CODE_TARGET);
@@ skipping 21 matching lines @@
     }
     case kArchTailCallJSFunction: {
       Register func = i.InputRegister(0);
       if (FLAG_debug_code) {
         // Check the function's context matches the context argument.
         __ LoadP(kScratchReg,
                  FieldMemOperand(func, JSFunction::kContextOffset));
         __ cmp(cp, kScratchReg);
         __ Assert(eq, kWrongFunctionContext);
       }
-      AssembleDeconstructActivationRecord();
+      int stack_param_delta = i.InputInt32(instr->InputCount() - 1);
+      AssembleDeconstructActivationRecord(stack_param_delta);
       __ LoadP(ip, FieldMemOperand(func, JSFunction::kCodeEntryOffset));
       __ Jump(ip);
       DCHECK_EQ(LeaveRC, i.OutputRCBit());
       break;
     }
     case kArchLazyBailout: {
       v8::internal::Assembler::BlockTrampolinePoolScope block_trampoline_pool(
           masm());
       EnsureSpaceForLazyDeopt();
       RecordCallPosition(instr);
@@ skipping 1030 matching lines @@
       padding_size -= v8::internal::Assembler::kInstrSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8